Core aeration should be done to correct problems of soil compaction and thatch buildup, not as a routine part of lawn care. Buying the right equipment is costly and you will use valuable storage space for equipment you will not routinely use. You may find it is cheaper and more effective to hire someone with the right equipment to do the job only when needed. If you decide to rent or buy the equipment select the machine that removes the plugs. The ones that punch holes into the soil only add to problems with compaction. Make sure the machine is powerful enough to get through the heavy compacted soils and can remove plugs several inches long. Those that grind the plugs for quicker breakdown provide even better results.